The invention relates to a tampon applicator and to a process for its production and an apparatus for carrying out this process. The tampon applicator has a domed expulsion end with petal-weakening features.
Tampon applicators having an applicator barrel and a plunger tube in a telescopic arrangement are commercially available. The applicator barrel generally contains a tampon and at least the front portion of the plunger tube. The barrel and plunger may be formed of a molded, thermoplastic material or a sheet-like material, such as paper and cardboard, coated paper, and the like. Recent developments have included the use of a rounded expulsion end formed of a plurality of curved segments known as petals. Tampons having this general construction are disclosed in Weigner, U.S. Pat. No. 4,412,833, Beastall et al., U.S. Pat. No. 5,087,239, Decker et al., U.S. Pat. No. 4,453,925, Frayman et al., WO 94/10959, Hinzmann, U.S. Pat. Nos. 4,302,174 and 4,755,164, and Hinzmann et al., U.S. Pat. No. 4,321,993.
It is now recognized that designers of such tampon applicators need to reduce the force needed to expel tampons. Thus, Weigner, Beastall et al., and Frayman et al. provide a hinge at the base of the petals. In addition, Frayman et al. provide a plurality of small cuts extending circumferentially from end of the slits and a plurality of circumferential score lines in about the hinge. Decker et al. also provides exterior score lines, claiming that they reduce wrinkling, spring-back and other detriments known in paper applicator tubes. However, these exterior score lines provide potential sources of irritation to users during insertion.
An object of the invention is to significantly reduce the force necessary to expel the tampon out of the applicator barrel, to increase insertion comfort for the user, and to provide a process and an apparatus which permit an efficient production of the tampon applicator, meeting the requirements demanded of mass production.
The invention achieves these objects by forming rounded petals at the expulsion end of the applicator. The petals are weakened on their inner surface and at an axial distance from the base of the segments where they transition to the cylindrical applicator barrel. This achieves the effect that the bending resistance to a bending out of the segments during ejecting of a tampon arranged in the applicator barrel is significantly reduced, because the width and the curvature of each segment are less at the hinge line running in the circumferential direction than at the segment base. The location of the lines of weakness on the inner surface of each segment at a distance between the hinge line and the free end of each segment further reduces expulsion force. The surface section of each segment lying in front of the hinge line generally opposes the expulsion forces acting outward in response to a bending out of the segments with less of a bending resistance. Thus, partially weakening the wall thickness of the petal material where they are curved to form the domed expulsion end acts to reduce expulsion forces needed. The smooth outer surface of the segments reduces irritation which may otherwise arise during use of the tampon applicator.
In forming the tampon applicator, a plurality of mutually separate, longitudinally extending segments or petals are cut out of at least one end of an applicator blank. The applicator blank is formed of a section of paper-like material. The sides of the blank are joined to produce the cylindrical applicator barrel, and the longitudinally extending segments are shaped to form petals in a dome with a central opening bounded by the front ends of the petals. A hinge line may be formed into the blank before it is formed into the cylindrical applicator barrel, or it may be formed in the formed applicator barrel. The hinge line is spaced toward the segment ends, away from their base where they transition to the cylindrical applicator barrel. At the same time, lines of weakness, extending substantially in the longitudinal direction of the applicator are formed in the inner surface of the petals, spaced toward the segment ends and separated from the circumferential hinge line.
An apparatus useful to form the tampon applicator and to practice the above process includes a stamping and notching apparatus. This stamping and notching apparatus has (a) a stamping head with a convex end face; (b) an outer die with a cylindrical recess and a concave base; and (c) notching jaws. The notching jaws are located in the stamping head and can be moved back and forth radially with respect to the longitudinal center axis of the stamping head by means of an actuating device. The notching jaws have notching edges which are arranged in a plane directed perpendicularly with respect to the main axis of the stamping head at angular intervals on an imaginary circle for forming hinge lines on the inner surface of triangular segments of an applicator barrel.